A conventional rectification device which converts AC power into DC power is configured such that, for example, a load is arranged on an output stage of a bridge type full wave rectification circuit composed of four diodes; a choke coil and a diode are connected in series to the load; and a resistor and a smoothing capacitor, which are connected in series to a switch element, are arranged in parallel to the load; and DC output power is supplied to the load. Then, the rectification device detects a current flowing through the resistor to control the switch element at a predetermined pulse width based on the result of the detection, and thus improves a power factor of the rectification device.
However, a problem exists in that conversion efficiency deteriorates due to loss of the diode and the like in the rectification device; and in a rectification device equipped with a power factor correction (PFC) circuit, two of four rectification elements that form the bridge type are replaced with switch elements in order to improve a power factor. For example, in a power supply device of PTL 1 shown in FIG. 10, two rectification elements on the side through which a feedback current of a bridge type full wave rectification circuit flows are replaced with switch elements 4a, 4b, respectively; a smoothing capacitor 5 provided on the next stage of the rectification circuit is connected to an AC input power source 1 via a choke coil 2; and a control circuit 6 that controls the operation of the switch elements 4a, 4b is provided so as to detect an input voltage, an output voltage, and currents flowing through the switch elements 4a, 4b. The control circuit 6 discriminates between an upper wave side portion and a lower wave side portion of a line input voltage, operates the switch elements 4a, 4b respectively according to the discrimination, and properly controls the pulse widths of the switch elements so that a line input current becomes a sine wave AC current having the same phase as the phase of the line input voltage. As described above, in a so-called bridgeless PFC in which two rectification elements through which the feedback current of the bridge type full wave rectification circuit flows are respectively replaced with the switch elements and the control circuit properly controls the switch elements, thereby improving the power factor, the number of components can be reduced and conversion efficiency and reliability can be improved.